The present disclosure relates to a fingerprint sensor and an electronic device including the same.
Fingerprint sensors are devices used to sense human fingerprints and have recently been used for determining whether to turn electronic devices on or off or whether to release a device from sleep mode, as well as having previously been applied to door locking apparatuses. In particular, unlike fingerprint sensors used in door locking apparatuses, swipe type fingerprint recognition sensors, commonly having small volumes, have been developed, and have been ever increasingly used in devices such as mobile devices.
Fingerprint sensors may be divided into ultrasonic type fingerprint sensors, infrared type fingerprint sensors, and capacitive type fingerprint sensors, depending on the operational principle thereof. Among these, ultrasonic type fingerprint sensors sense a fingerprint in a manner in which, when ultrasonic wave signals having a specific frequency are emitted from a plurality of piezoelectric sensors and are reflected from valleys and ridges of a fingerprint, differences in acoustic impedance between signals reflected from valleys and those reflected from ridges are measured by the very same piezoelectric sensors which have emitted the ultrasonic wave signals. In addition to simply detecting fingerprints, ultrasonic type fingerprint sensors have an advantage in that they may generate ultrasonic waves in pulse form so as to detect the Doppler effect due to pulse reverberations, so that bloodstream in a finger may be detected, thereby preventing the use of fake fingerprints.
Recently, ensuring the security of mobile devices such as laptop computers and mobile phones has become an important issue, and accordingly, fingerprint sensors have been increasingly employed therein. However, since mobile devices are constantly being reduced in size, it may be difficult to install fingerprint sensors therein, and even if such sensors are installed, a degree of freedom of the positioning thereof may be somewhat limited.